An observational study of the effects of changes in functional residual capacity on patients with simple obstructive sleep apnea hypopnea syndrome

Abstract

Objective: To observe the effect of changes in functional residual capacity（FRC）on the severity of patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: A total of 256 patients with OSAHS diagnosed by night polysomnography (PSG) were enrolled, including 208 males and 48 females. The patients were recorded with sleep hypopnea index (AHI), oxygen reduction index(ODI), arousal index(ArI), total sleep time(TST), maximum apnea time(MAT), average apnea time(AAT), mean oxygen saturation (MSaO2), lowest oxygen saturation (LSaO2), oxygen saturation below 90% of the total recording time (TP90%) and other indicators. All subjects underwent pulmonary function tests to measure residual lung volume index (RV), functional residual capacity (FRC), and total lung volume (TLC). All subjects were divided into three groups in terms of less than or equal to 80%, 80% to 110% and greater than 110%. The sleep related indexes such as AHI, ArI, ODI, TST, MAT, AAT, MSaO2, LSaO2 and TP90% were compared among the groups. Results: In the case of similarity in sex, age, BMI, and degree of pharynx ( no statistically significant difference between groups), AHI, ODI, ArI, MSaO2, LSaO2 and TP90% were statistically different between groups(P 0.05). Conclusion: The patients with OSAHS whose functional residual capacity is higher have a relatively milder condition. The increase of functional residual capacity can improve the degree of upper airway collapse and increase the stability of upper airway, thus improving severity of OSAHS patients.